First dog, that's brilliant
As Sharon says, go for Lifetime cover with a limit of at least £5k per year although £7k or £10k should be considered given the high cost of some specialist treatments and the variation in cost of veterinary care across the country.
Keep in mind that any insurance product pushed by your vet will almost certainly be the best one….For your vet
but may not be the best for you.
Have a good look through these Insurance pages to get some idea of the pitfalls that can lie in wait even with the biggest and most heavily advertised companies.
With some companies you'll get a small discount for paying the premium in one lump while others will allow monthly payments at no extra cost. Some companies give a discount for a second (or third, fourth, fifth) dogs as well.
To give you some idea, we've two cockers on £7k lifetime policies at a cost of around £200pa each but we live in North East Scotland where vet costs are somewhat lower than other areas of the country
Best of luck with your new dog and your hunt for a reasonable insurance provider.
Bob.